Reversible air conditioning system with hot gas defrosting means



HOT GAS DEFROSTING MEANS Filed Nov. 5, 1954 IIIIIIIIL Nov. 18, 1958 D. GOLDENBERG REVERSIBLE AIR CONDITIONING SYSTEM WITH INVENTOR L2 ATTORNEY 2,860,491 Patented Nov. 18, 1958 ii'ice REVERSIBLE AIR CONDITIGNING SYSTEM WITH HOT GAS DEFROSTING MEANS David Goldenberg, Trenton, N. 3., assignor to Kramer Trenton Company, Trenton, N. J., a corporation of New Jersey Application November 5, 1954, Serial N 0. 467,115

Claims. (Cl. 62--161) This invention relates to a reversible air conditioning system with hot gas defrosting means and has for an object to provide such a system which includes indoor and outdoor coils and in which the outdoor coil can be defrosted during cold weather without the necessity of chilling the indoor space served by the indoor coil.

Another object is to provide such a system in which is positioned heat storage means that is warmed during both the cooling cycle and heating cycle (i. e., warm weather and cold weather) of the system and supplies heat for aiding in the reevaporation of the refrigerant that has been condensed in the outdoor coil during its defrosting and is returning to the compressor.

Another object is to provide such a system in which the heat storage means is small and compact, and embodies a coil, or the like, which is immersed in liquid that may freeze during defrosting cycles to give up its heat of fusion to the condensed refrigerant flowing through the said coil and, in turn, may melt during the heating cycles which follow.

Another object is to provide such a system in which the changes from cooling cycle to heating cycle, and vice-versa, as well as the occurrence and duration of defrosting cycles, are governed by the operation of a suitable flow control device, such as a 4-way valve.

Another object is to provide such a system which embodies means for obviating friction. pressure drop of the refrigerant returning to the compressor during defrosting cycles due'to passage through the indoor coil.

Another object is to provide such-a system in which the last named means comprises a by-pass construction that also eliminates the requirement for certain control valves and piping.

A further object is to provide certain improvements in the form, construction, and arrangement of the several parts whereby the above named and other objects inherent in the invention may be effectively attained.

In brief summary, the invention comprehends an air conditioning system for buildings, which system includes both indoor and outdoor coils, or the like, that serve reversibly as evaporator and condenser for cooling the building interior in warm weather and warming it in cold weather; the outdoor coil being exposed to atmosphere. A characteristic of the system is the provision of heat storage means which accumulates heat during both the cooling and heating cycles of the system, whereby the outdoor evaporator can be defrosted by hot gas from the compressor and the resultant condensed refrigerant be reevaporated before it returns to the compressor. A modification involves'the presence of means for bypassing the indoor evaporator during defrosting cycles to reduce friction pressure drop in the refrigerant flowing tothe compressor.

Practical embodiments of the invention are shown in the accompanying drawing, in which,

Fig.-1 represents a diagrammatic layout of the system; and

Fig. 2 represents a similar view of a modified form.

Referring to Fig. 1, the compressor is denoted by 1, and may be of any suitable type, hermetically sealed or otherwise. lts discharge conduit 2 is in communication with one port of a 4-way reversing valve 3; which is not deemed to require structural illustration or description in view of the fact that its characteristics are well understood by engineers in this field and such valves are obtainable in the open market, e. g., the product of Alco Valve Company, St. Louis, Mo. A second port of the valve is connected by a conduit 4 with the compressor intake; a third port is connected by a conduit 5 with the indoor coil 6; and the fourth port is connected by a conduit 7 with the outdoor coil 8. The arrangement of the valve ports is such that, in one position of the valve, the compressor discharge communicates with the outdoor coil and the compressor intake communicates with the indoor coil, while, in another valve position, the said communications are reversed.

The indoor coil 6 is fitted with the usual fan and motor, marked 9 collectively, and. the same is true of the outdoor coil 8, where the fan and motor are denoted by 10. The said coils may be of conventional, or any appropriate, form and construction, adapted to serve as evaporators'and also as condensers according to the refrigerant flow setting of the system; and the fan motors should be controlled by some means, preferably automatic, for causing the fans to rotate or remain idle according to the then cycle of operation of the system, all as is so well understood by engineers in this field as to call for neitner illustration nor further description.

The outdoor coil 8 is also connected by a conduit 11, in which is positioned a suitable check valve 12, with the receiver 13, for the fiow of refrigerant to the receiver when the system is operating on one cycle; and a bridging tube 14, fitted with an appropriate pressure reducing device, such as a thermostatic expansion valve 15, connects with conduit 11 at two points for the flow of refrigerant from the receiver to coil 8 when the system is operating on another cycle. The valve 15 is controlled by the usual feeler bulb 16.

A conduit 17 connects the receiver 13, through a solenoid valve 18, with a reevaporator which is preferably similar to that disclosed in U. S. patent application Serial No. 388,587, filed by Israel Kramer on October 27, 1953, now Patent No. 2,718,764, issued September 27, 1955. This may be briefly described as consisting of a container or tank 19, conveniently rectangular in shape and composed of steel or other proper material, which is filled with a freezable liquid, such as water, generally without any freeze depressant, such as denatured alcohol. In container 19 is located a coil 20 of any desired form, manifolded or otherwise. One end of coil 211 connects with conduit 17, and the other end with a conduit 21 that leads, through a pressure reducing device, such as a thermostatic expansion valve 22, to the indoor coil 6. Valve 22 is controlled by feeler bulb 23. A by-pass conduit 24 bridges solenoid valve 18, and a restrictor, such as a hold back valve 25, is located in the by-pass. A pair of by-pass conduits, 26 and 27, bridge expansion valve 22. In by-pass 26 are positioned a solenoid valve 28 and a check valve 29, which latter permits fiow toward reevaporator 19, 20. In by-pass 27 are positioned a solenoid valve 30 and a check valve 31, the latter permitting flow toward the indoor coil 6. The points at which conduits 17 and 21 enter container 19 are suitably sealed for liquid tightness,-as by stufiing boxes.

For operation on the cooling cycle, the 4-way valve 3 is set to open communication between the discharge of compressor 1 and the outdoor coil 8 through conduits 2 and 7, while the solenoid valve 18 is open and solenoid valves 28 and 30 are closed. The hot refrigerant gas newt-flows from' the compressor to the outdoor coil 8 whichfunctions as acondenser to liquefy the gas which passes through. conduit 11 and check valve 12 to be deposited :in receiver 13. From the latter the refrigerant -travelsdh'rough conduit 17, solenoid valve 18, coil 20, conduit 21,and expansion valve 22, to indoor coil 6, which =1atter now serves as an evaporator to cool the surrounding air .Whichis circulated by fan 9. From the indoor coil, the vaporized refrigerant traverses conduit 5, the 4-way valve 3, and conduit 4 to the compressor intake for recompression and re-circulation as just described. During .this coolingcycle, the warm refrigerant imparts heat to theliquid within container 19, but the coil does not function as a reevaporator.

When, 'as the result of seasonal change or for any other reason, it is desired to reverse the system to its h eating cycle and thus warm the building enclosure in which the indoor coil 6 is located, the 4-way valve is turned to connect the discharge of compressor 1 with the indoor coil through conduits 2 and 5, while the compressor intake is co'nnected with the outdoor coil 8 through conduits4 and 7. Solenoid valve 18 is left open, solenoid -valve is left closed, and solenoid valve 28 is opened. The hot refrigerant gas now flows to'the indoor coil 6, which functions as a condenser, and its fan 9 circulates the surrounding air which is warmed by the coil. The condensed refrigerant moves from the indoor coil through b'y-pas s 26, solenoid'valve 28, check valve 29, conduit '21,'-coil '2 0, conduit 17, and solenoid valve 18, to the receiver 13. From. the latter the flow is through tube 14 to expansion'valve .15 which lowers the pressure, and to the outdoor coilwhere'evaporation takes place due to heat obtained'from the ambient air blown over the "coil 'by its fan. The vaporized refrigerant thence procee'ds through conduits'7 and 4 to the compressor intake for re-compression and re-circulation.

'When operating on the heating cycle just explained, the outdoor 'c'o-il accumulates frost,-es-pecially when the temfperature dropsto, say, F. or lower, and eflicient performance calls for defrosting at appropriate intervals. "This has heretofore been accomplished in systems of this general type by intermittent reversing to the cooling cycles in whichheat'is abstracted from the indoor air anchor gas isfed to the outdoor coil. This procedure, however, chills the indoor space and establishes an uncomfortable, if not intolerable, condition therein. To offset-this, resort has been had to the provision of electric iheatingmeans for the indoor space, operative during defrosting, which, of course, not only complicates the setupjbut likewise 'adds'materially to first costand maintenan'ce' expense,- includingelectrical demand charges. The -presentinvention eliminates the just'recited disadvantages by embodying defrosting means that comes into action in anope'ratingcycle differing fro-m both the cooling and heatingcycles,-*as will now be described.

'-'-To i'nitiate a defrosting cycle, the 4-way valve 3 is turned from itssetti'ng for the heating cycle, to its setting for the cooling cycle, solenoid valve '18 is closed, solenoid valve 30 is opened; "and solenoid valve 28 is closed. The hot gasfro'rn'the discharge of compressor 1 now flows directly' to the outdoorcoil 8 and melts the frost thereon. In actiomplishing'this, the gas is condensed and passes iri liq'uid"phase through conduit 11 and check valve 12 into thefreceiver 13. i From the latter the flow is through "c'otiduit 17 and'by-pass 24 to hold back valve 25. This "va'l've' isadjusted or set to discharge the refrigerant at low/temperature, elf g. 20 F. or lower, and it thus serves "as an expansionvalvefunctioning to reduce the high temperature, high pressure liquid refrigerant into a' low temperature, low pressure mixture of liquid and gas or vapor. The refrigerant in this form passes along to the coil 20 which now becomes a reevaporator with'the low temperature of the refrigerant freezing the warm water in container or tank 19 and its liquid portion being in turn, vaporized by the latent heat of fusion. In this gaseous phase the refrigerant travels through conduit 21, by-pass 27, check valve 31, solenoid valve 30, to the indoor coil 6. As the flow is in vapor phase it passes through coil 6 without evaporation and, hence, does not appreciably affect the air temperature of the enclosure within which the said coil is located. The cycle is completed by passage of the low pressure gas through conduit 5, the 4-way valve 3, and the conduit 4 to the compressor intake.

During defrosting the fan 10 associated with the outdoor coil is idle, and the fan 9 associated with the indoor coil may be either idle or running.

Following completion of defrosting the outdoor coil, the system may be returned to the heating cycle by turning the 4-way valve so that the compressor discharge is connected with the indoor coil and its intake is connected with the outdoor coil, openingsolenoid valve 18, closing solenoid valve 30, and opening solenoid valve 28. The

indoorcoil never requires defrosting because, even on the cooling cycle, the refrigerant temperature therewithin is above the freezing point.

.The solenoid valves '18, 728,30,- as well as the motors for fans 9 and 10,,may be automatically operated by any suitable electrical control system, with which engineers skilled in this field are so familiar as to require neither illustration nor description. Thus, for example, the defrosting cycle may 'beinitiated' and its duration determined by -an electrical timer or by a pressure switch responsive to pressure at the intake of'the compressor. If a timer is used, it may be held outof operation by a thermostat responsive' to'a'mbient air temperature at the outdoor coil "sothat' it 'Will'not be effective until there is a fall to, say, "'50"-"F;or lower. It is usually satisfactory to have manual control for the 4-way valve to reverse from cooling cycle "to heating'cy'cle, and viceversa, but it should be auto- 'in it are positioned a solenoid valve. .33 with a. check 'valve 34; the conduit itself spanning theindoor coil 6 and being connected with conduits 21.and 5.

This modification is useful only in the defrosting cycles. During the other two cycles (cooling:and heating), the solenoid valve-331is closed andthe system operates exactly as already described'when explaining the form of Fig. 1. Wherra defrosting cycle is initiated, valve 33 opens,*valve' 18 closes,-and the-system functions. to defrost the outdoor coil .as -'set forth in connectionwith Fig. 1. "Howevenin the modified form,.the reevaporated gaseous refrigerant flowing from the reevaporator. 19, 20, travels through conduit 21 into the by-pass 32 and through valves 34' and 33 to conduit 5. -This .eliminates friction pressure drop occasioned by passage throughtheindoor coil 6 and hence 'maintains higher operating efficiency of the compressor by'supplying-the refrigerant to its intake at a pressure higher than would beithe case if.its course of travel included the indoor'coil. Further, as above,1ndicated, there is an appreciable economy derived from the fact that'this modification eliminates two. solenoid valves, "28 and 30, whileadding only'one," 33. .It is also possible tosimplify the design and reduce thelcost of the indoor coil when the by-pass 32 is included'in' the system. .Solenoid 'valve 33' may be involved imthe electrical. control hereinabove described.

With reference to bothforms of; the :invention, it is preferable to have the container or tank 19 permanently filled with water, but, if desired for any reason, it could be connected to a source of water supply and be provided with a drain. In such an arrangement, the container will be filled with warm water for the defrosting cycles, and the subsequent melt from the ice encrustation on the coil 20 be drained off. Needless to say, such a provision would be less practicable and more costly than the permanent filling of the container or tank.

Again referring to both forms of the invention, it will be clear that provision is made not only for indoor temperature conditioning at all seasons of the year and in differing climatic Zones, but also for efficient defrosting of the outdoor coil without material effect upon the indoor temperature, and without requiring the presence of temporary auxiliary heating means for the indoor space.

It will be understood that various changes may be resorted to in the form, construction, and arrangement of the several parts of the system without departing from the spirit or scope of the invention; and, hence, I do not intend to be limited to details herein shown or described except as the same may be included in the claims or be required by disclosures of the prior art.

What I claim is:

1. A system of the character described including a refrigerant compressor having its discharge and intake connected by conduits with indoor and outdoor coils or the like, said system comprising, reversible refrigerant flow controlling means positioned in the conduits between the compressor and the indoor and outdoor coils for causing the indoor coil to function as an evaporator in cooling cycles of the system and to function as a condenser in heating cycles of the system and causing the outdoor coil to function as a condenser in cooling cycles of the system and to function as an evaporator in heating cycles of the system, said flow controlling means being also adapted for causing hot gas flow from the compressor discharge to the outdoor coil for defrosting the latter without causing the indoor coil to function either as an evaporator or a condenser, means positioned between the indoor and outdoor coils and in heat exchange relation with conduits connecting both said coils for storing heat during both the cooling and heating cycles of the system, and means conduit connected between the indoor and outdoor coils for refrigerant flow from the latter to the former for reevaporating refrigerant that has been condensed in the outdoor coil during defrosting.

2. A system of the character described including a refrigerant compressor having its discharge and intake connected by conduits with indoor and outdoor coils or the like, said system comprising, reversible refrigerant fiow controlling means positioned in the conduits between the compressor and the indoor and outdoor coils for causing the indoor coil to function as an evaporator in cooling cycles of the system and to function as a condenser in heating cycles of the system and causing the outdoor coil to function as a condenser in cooling cycles of the system and to function as .an evaporator in heating cycles of the system, said how controlling means being also adapted for causing hot gas flow from the compressor discharge to the outdoor coil for defrosting the latter without causing the indoor coil to function either as an evaporator or a condenser.

3. A system of the character described including a refrigerant compressor having its discharge and intake connected by conduits with indoor and outdoor coils or the like, said system comprising, reversible refrigerant flow controlling means positioned in the conduits between the compressor and the indoor and outdoor coils for causing the indoor coil to function in both cooling and heating cycles of the system, said flow controlling means being also adapted for causing hot gas flow from the compressor discharge to the outdoor coil for defrosting the latter, a receiver connected by refrigerant flow conduits with the indoor and outdoor coils, a reevaporator positioned in the conduit connecting the receiver with the indoor coil for reevaporating refrigerant condensed in the outdoor coil during defrosting and flowing toward the indoor coil, and a pressure reducing device interposed be tween and connected by refrigerant flow conduits with the receiver and reevaporator for cooperative functioning with the latter during defrosting.

4. A system as defined in claim 3, which also comprises a shut-off valve positioned in the conduit between the receiver and the reevaporator and a by-pass conduit spanning said valve, and in which the pressure reducing device is positioned in said by-pass conduit.

5. A system of the character described including a refrigerant compressor having its discharge and intake connected by conduits with indoor and outdoor coils or the like, said system comprising, reversible refrigerant flow controlling means positioned in the conduits between the compressor and the indoor and outdoor coils for causing the indoor coil to function in both cooling and heating cycles of the system, said flow controlling means being also adapted for causing hot gas flow from the compressor discharge to the outdoor coil for defrosting the latter, a receiver connected by refrigerant fiow conduits with the indoor and outdoor coils, a reevaporator positioned in the conduit connecting the receiver with the indoor coil for reevaporating refrigerant condensed in the outdoor coil during defrosting and flowing toward the indoor coil, and heat storage means combined with the reevaporator and arranged to be warmed during the cooling and heating cycles of the system.

6. A system as defined in claim 5, in which the heat storage means is in heat exchange relation with the conduit between the receiver and the indoor coil.

7. A system as defined in claim 6, in which the reevaporator embodies a container and a coil therewithin, and in which the heat storage means is a freezable liquid in the container contacting the coil.

8. A system of the character described including a refrigerant compressor, indoor and outdoor coils or the like connected by conduits with the compressor discharge and intake, a receiver positioned between said indoor and outdoor coils, reevaporating means positioned between the receiver and the indoor coil, and reversible refrigerant flow controlling means positioned in the conduits between the compressor discharge and intake and the indoor and outdoor coils, said system embodying means for causing the indoor coil to function as both a cooling and a heating unit and for defrosting the outdoor coil, said last named means comprising, two conduits interconnecting the outdoor coil and the receiver one equipped with means permitting flow toward the receiver but inhibiting reverse flow and the other equipped with pressure reducing means operative when flow is toward the outdoor coil, two conduits interconnecting the receiver and the reevaporating means one equipped With means to close flow therethrough and the other equipped with flow restricting means operative when flow is toward the reevaporating means, three conduits interconnecting the reevaporating means and the indoor coil two equipped with means to close fiow therethrough and one of the said two also equipped with means permitting flow toward the indoor coil but inhibiting reverse flow while the other of said two is also equipped with means permitting flow toward the reevaporating means but inhibiting reverse flow and the third said conduit being equipped with pressure reducing means operative when flow is toward the indoor coil.

9. A system as defined in claim 8, in which heat storage means is combined with the reevaporating means and is warmed by the circulating of refrigerant when the indoor coil is functioning as a cooling unit and also when the latter is functioning as a heating unit.

10. A system of the character described including a refrigerant compressor, indoor and outdoor coils or the like connected by conduits with the compressor discharge and intake, a receiver positioned between said indoor and outflow controlling means positioned in the conduits between the compressor discharge and intake and the indoor and outdoor coils, said system embodying meansfor causing the indoor coil to function as both a cooling and a heating unit and ;for,clefrosting the outdoor coil, said last named means comprising, .two conduits interconnecting the out- 1door.coil.and the receiver one equipped with means permitting flow .toward the receiver ,but inhibiting reverse flow and the otherequipped with.pressure reducing means operative ,whenflow is toward the outdoor coil, two con- .duits interconnecting the receiver and the reevaporating means one equipped with means to close flow therethrough and the other equipped with flow restricting means operative when flow is toward the reevaporating means, two conduits interconnecting the reevaporating e reeva q at n me n a i e 11 .4 0: q t at a mm between the reevaporating means andthelastnamed-pressure reducing means with the conduit between tlie indoor coil and the compressor at a point betweenthe indoor coil and the flow controlling means, said third conduit being equipped with means ,to close flow therethroughand with means permitting flow toward ,the flow controllingmeans .but inhibiting flow inthe oppositedirec tion,

References Citedjn the file of this patent UNITED STATES PATENTS 1,935,281 Reed Nov. 14, 1933 2,440,146 Kramer Apr. 20, 1948 2,530,440 .Nussbaum Nov. 21, 1950 2,534,031 Kollsman Dec. 12,1950 2,630,685 Lewis Mar. 10, 1953 2,632,303 Smith .Mar. 24, 1953 2,694,904 Lange Nov. 23, 1954 2,713,247 Terry etal. 'July 13, ,1955 2,725,724 Rosen Dec. 6, 1955 2,726,067 Wetherbee et a1. Dec. 6, 1955 

